Integrins expressed on the endothelial cells were characterized as an important element of angiogenesis. The alpha 1 beta 1 integrin is a collagen type IV receptor and is highly expressed on cardiac human microvascular endothelial cells (cHMVEC) and is very sensitive target for inhibition of these cells migration and proliferation. In proposed research plan, we will focus on investigation of recombinant snake venom KTS-disintegrins, obtustatin and viperistatin, which were previously characterized as potent inhibitos of alpha 1 beta 1 integrin. Synthetic peptides of obtustain will be produced and mutated into viperistatin which is close to two orders of magnitude higher activity than obtustatin inhibition of alpha 1 beta 1 integrin in vitro. The activity of the recombinant disintegrins will be monitored in adhesion and flow cytometry assays. Next, testing activities of the recombinant disintegrins will include inhibition of cHMVEC proliferation, migration in collagen matrix and induction of apoptosis. These studies will clarify correlation between structure and function of these biologically active molecules and will be helpful for explanation of role of alpha 1 beta 1 integrin in cardiac angiogenesis.